determination of sulphur compounds in 
DRY LIME-SULPHUR 1 
By Carleton Parker Jones 
Assistant Research Professor of Chemistry , Massachusetts Agricultural Experiment Station 2 
INTRODUCTION 
Lime-sulphur products and analogous substances, known as polysul- 
phids, have of recent years come into prominence because of thSir value as 
insecticides and fungicides. Large quantities, especially of the lime- 
sulphur compound, are now manufactured. Correct and simple methods 
are needed for the estimation of the principal constituents, both as a safe¬ 
guard to the producer and as a help to the entomologist and plant patholo¬ 
gist. 
METHODS IN USE 
Avery ( 2 ), 3 working with sulphur dips, modified standard methods in 
order to determine the total sulphur and total lime. Na^, resulting from 
the treatment of a dilute solution with NaOH, was oxidized by a large 
excess of medicinal H 2 0 2 . 
Haywood ( 6 y 7), also modified standard methods in order to estimate 
the sulphur combined as sulphids, polysulphids, and thiosulphates. The 
sulphid sulphur was determined by titration with standard ammoniacal 
ZnCl 2 , using NiSCL as an outside indicator. The ZnS was converted into 
soluble sulphid by treatment with an excess of a saturated solution of 
KOH. The alkali sulphid was then oxidized by means of a large excess of 
H 2 0 2 . The thiosulphate was determined in another ,portion of the solu¬ 
tion, after the removal of the soluble sulphids as explained by titration 
with standard iodin. . v ' * 
Thompson and Whittier (9) determined the monosulphid sulphur by 
the addition of a slight excess of ammoniacal CdCl 2 to the solution of 
the polysulphid in the presence of KCN. The precipitated CdS was 
then dissolved in NaOH and the resulting Na^ was oxidized with 
H 2 0 2 . The thiosulphate sulphur was determined in a separate portion 
by titration of the filtrate, from the ammoniacal CdCl 2 precipitation, 
with standard iodin. The total sulphur was estimated by precipitation 
with ammoniacal CdCl 2 and treatment of the’precipitate as given under 
the monosulphid sulphur determination. The authors state that this 
method is unaffected by any free Ca(OH) 2 or S in solution. 
The methods employed by Tartar and Bradley (8) consisted in the 
use of N /10 ammoniacal ZnCl 2 with NiS0 4 as an outside indicator, for 
the determination of the monosulphid sulphur, and a titration method, 
N /10 HC1 being used with methyl orange as indicator, for the estimation 
of the polysulphid sulphur. The deposited sulphur was weighed 
directly, or for more accurate results, recommendation was made to 
bring the sulphur into solution with KOH and then to oxidize with 
1 Accepted for publication May a, X923. 
3 Published with the authorization of the director of the Massachusetts Agricultural Experiment Station. 
* Reference is made by number (italic) to “ Literature cited/' p. 336. 
Journal of Agricultural Research, 
Washington, D. C. 
aga 
(323) 
Vol. XXV, No. 7 
Aug. 18, 1923 
Key No. Mass.-9 
